I just happen to have the Newfoundland Travel Guide here, and I discover the following:
(1) Grand Codroy RV Camping Park, open until mid-Oct. Doyles, NL (that's "Newfoundland and Labrador"), 36 km from Port aux Basques.
(2) Lomond River Lodge Campground, open until mid-Oct., Lomond River, Route 431, on the edge of Gros Morne National Park.
(3) Gros Morne National Park, open year round.
...and other campgrounds open around the park until mid. Oct. One is open year round with unserviced sites.
(4) Country Inn Trailer Park, Gander, open until Oct.31.
(5) Indian Bay Connections, near Trinity, open until Oct. 30.
....and one in Eastport (open until Oct.16)
(6) Mountain View RV Park and Droghedea R.V.Park, Clarke's Beach (where I live), 90 km from St. John's.
(7) Cochrane Pond Family Campground, year round, 10 kms. or so from St. John's
That just about takes you across the Island. And the stories of Newfoundland weather closing in early are greatly exaggerated. We usually have lovely fall
weather. Our problem is we have no spring -- so I usually escape
to the mainland in May to avoid the cold, miserable weather when the ice comes down. There might be the occasional frost in October and November, but the snows rarely come before December.
If this attracts you to our fair province, do get the same guide I have. Call 1-800-563-NFLD, or go to the website: www.gov.nf.ca/tourism